On Fri 28/May/2021 17:43:37 +0200 Todd Herr wrote:
Consensus on Ticket #47 <https://trac.ietf.org/trac/dmarc/ticket/47> (Removal
of "pct" tag) was reached during the May 27 DMARC Interim to keep the tag, but
to rewrite its definition in whole or in part to make its usage better understood.
I think the text in RFC 7489 is quite good. Perhaps a word could be added for
pct=0; for example:
OLD
pct: (plain-text integer between 0 and 100, inclusive; OPTIONAL;
default is 100). Percentage of messages from the Domain Owner's
mail stream to which the DMARC policy is to be applied. However,
this MUST NOT be applied to the DMARC-generated reports, all of
which must be sent and received unhindered. The purpose of the
"pct" tag is to allow Domain Owners to enact a slow rollout
enforcement of the DMARC mechanism. The prospect of "all or
nothing" is recognized as preventing many organizations from
experimenting with strong authentication-based mechanisms. See
Section 6.6.4 for details. Note that random selection based on
this percentage, such as the following pseudocode, is adequate:
if (random mod 100) < pct then
selected = true
else
selected = false
NEW
pct: (plain-text integer between 0 and 100, inclusive; OPTIONAL;
default is 100). Percentage of messages from the Domain Owner's
mail stream to which the DMARC policy is to be applied. However,
this MUST NOT be applied to any other use, such as skipping DMARC
reports or demeaning a domain's policy. The purpose of the
"pct" tag is to allow Domain Owners to enact a slow rollout
enforcement of the DMARC mechanism. Using this tag, organizations
can experiment with strong authentication-based mechanisms while
lowering or even voiding the risk of non-delivery. See Section 6.6.4
for details. Note that random selection based on this percentage,
such as the following pseudocode, is adequate:
if (random mod 100) < pct then
selected = true
else
selected = false
jm2c
Ale
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